com.turn.splicer.hbase.MetricsCache.java Source code

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Here is the source code for com.turn.splicer.hbase.MetricsCache.java

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/**
 * Copyright 2015-2016 The Splicer Query Engine Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.turn.splicer.hbase;

import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.concurrent.ExecutionException;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MetricsCache {

    private static final Logger LOG = LoggerFactory.getLogger(MetricsCache.class);

    protected RegionUtil regionUtil = new RegionUtil();

    protected LoadingCache<String, byte[]> cache = null;

    private static MetricsCache CACHE = new MetricsCache();

    private MetricsCache() {
        cache = CacheBuilder.newBuilder().maximumSize(1_000_000).build(new KeyFetcher(regionUtil));
    }

    public static MetricsCache get() {
        return CACHE;
    }

    static class KeyFetcher extends CacheLoader<String, byte[]> {

        private final RegionUtil regionUtil;

        public KeyFetcher(RegionUtil regionUtil) {
            this.regionUtil = regionUtil;
        }

        @Override
        public byte[] load(String metric) throws Exception {
            Configuration config = regionUtil.getConfig();
            try (HTable table = new HTable(config, "tsdb-uid")) {
                Get get = new Get(toBytes(metric));
                get.addColumn(toBytes("id"), toBytes("metrics"));
                Result result = table.get(get);
                LOG.info("Looking up key for metric={}. Found result={}", metric, Arrays.toString(result.value()));
                return result.value();
            }
        }
    }

    static byte[] toBytes(String str) {
        return str.getBytes(Charset.forName("ISO-8859-1"));
    }

    public byte[] getMetricKey(String metric) {
        try {
            return cache.get(metric);
        } catch (ExecutionException e) {
            LOG.error("Error loading value to cache", e);
            throw new MetricLookupException("Error loading value to cache", e);
        }
    }
}